DAMASCUS -- The man who ordered planes hijacked and Jews killed sat weakly in his chair, fidgeting with his left hand to straighten the curling thumb of his paralyzed right.

He complained that his fellow Palestinians were not being democratic.

George Habash, leader of a radical guerrilla group that staged spectacular terrorist attacks for 25 years, is reduced to this: an aging, enfeebled man griping about the unfairness of the pact between Israel and the Palestine Liberation Organization, and boasting when some young zealot gives up his life in another attack on Israelis.

"We will fight this agreement through an escalation of the intifada, through the armed struggle against Israel and through mustering Palestinian forces who oppose the agreement," vowed Mr. Habash, head of the Popular Front for the Liberation of Palestine.

As the timetable on the agreement between Israel and the PLO took effect yesterday and officials of both sides met in Egypt, the naysayers among the Palestinians looked on from the sidelines in Syria.

Mr. Habash, 64 and partly paralyzed by a stroke, is leader of the largest of 10 groups who formed the "rejectionist front" vowing to wreck the agreement.

They have been among the bitterest "rejectionists" of every move toward conciliation between the Arabs and the Israelis for more than two decades.

Mr. Habash's PFLP and the third-largest group in the PLO, the Democratic Front for the Liberation of Palestine, announced yesterday their plans to force the ouster of Yasser Arafat as chairman of the PLO and to replace him with a new, hard-line leadership.

Their capacity to cause suffering is real. In an interview Tuesday, Mr. Habash claimed responsibility for two attacks in Israel last week. A Palestinian on a power ski was killed nearing shore, and two Israeli hikers east of Jerusalem were slain by unknown assailants.

At least two other Palestinian groups also have said they sent those attackers. But the credentials of Mr. Habash are unquestioned: He inaugurated his organization in 1967 with the hijacking of an Israeli El-Al airplane, once hijacked three airliners at once, and masterminded a string of grotesque terrorist attacks for more than two decades.

Politically, the opposition groups have now been relegated to the proverbial voice in the wilderness, protesting as historic handshakes, peace agreements and the stirrings of a Palestinian government overtake their objections at drum-roll pace.

The autonomy agreement is being implemented, Mr. Arafat is preparing to move into the West Bank, and nations are lining up with money and support to ensure that the plan does not fail.

Perhaps only dramatic violence can stop the agreement now. Shimon Peres, Israel's foreign minister, told fellow Israelis this week to expect new terrorist attacks. And Mr. Arafat reportedly foiled an assassination plot against him by arresting at least nine bodyguards.

The rejectionist groups include old comrades and old foes of Mr. Arafat. Mr. Habash and fellow Marxist Nayef Hawatmeh lead the second- and third-largest factions, respectively, in the PLO, behind the Fatah faction of Mr. Arafat.

Also included are Ahmad Jabril, a long and bitter rival who has urged that Mr. Arafat be killed, and the Hamas Islamic fundamentalist group.

"Strange bedfellows is an understatement," said a western diplomat, who would not be named. "They agree on very little, except they are opposed to this agreement."

"We can't say we are completely comfortable working with Hamas," acknowledged Mr. Hawatmeh, whose Democratic Front for the Liberation of Palestine is avowedly non-religious.

The groups historically have found an accommodating home in Damascus. Syria has always played a leading role in the so-called "rejectionist front." Today, Damascus is angry that the PLO made a separate deal with Israel, undercutting the all-for-one strategy to which they were sworn.

To remind Israel and the PLO it cannot be left out, Damascus has not only permitted the groups to meet here but has been helpfully ushering foreign reporters to see them.

"The Syrians have a couple of cards. One of them is the rejectionists," said the diplomat. "When they feel things are not going in the right direction, they like to wave the card around."

If Syria reaches an agreement with Israel, however, one of the terms of the pact undoubtedly will be to quash activities of the Palestinian opposition groups. Mr. Habash and the others then would have to find a new home -- the few likely hosts are Iran, Sudan or Libya -- or become non-violent political players in the new Palestinian entity.

There are signs of a shift toward a political role already. Hamas, the strongest opposition group inside the occupied territories, has been hinting it would run in elections.

At a meeting in Damascus last week, the rejectionist groups failed to agree on an "alternate leadership" to Mr. Arafat. Instead, Mr. Habash talks of reforming the PLO.